1. Field of the Invention
This invention relates to modification to the method of adjustment of seat depth and height of chair plates, and the height of food tray and/or grab rail on adjustable chair for children.
2. Discussion of Prior Art
The classic adjustable chair for children described in U.S. Pat. No. 4,109,961 is capable of accommodating children of various ages to adults with different heights by adjusting the height of the seat plate. The patent uses a series smooth-surfaced horizontal groove arranged vertically on inner surface of the uprights (or upright panels) and facing each other. A foot rest plate and a seat plate, both having opposite ends respectively slide in opposite ones of the grooves at desired vertical locations along the upright panels. These chair plates are tightly held in place by tension and friction force between the two upright panels and the plates. The tension created by tightening screws and nuts on the upright panels. This method of adjustment requires significant time and effort requiring significant amount of human strength to ensure tightness of the screws and nuts. Moreover, one or more tools are required to loosen and tightened screws and nuts.
In addition, the series of horizontal grooves only applied to inner upright panels and not on outer upright panels to support the synchronization of the food tray or grab rail with the position of the seat. As a result, a growing child will end up with a food tray at higher position than usual, causing improper seating in the adjustable chair.